TY - JOUR
T1 - Efflorescence kinetics of aerosols comprising internally-mixed ammonium sulfate and water-soluble organic compounds
AU - Xu, Yeming
AU - Liu, Pai
AU - Ma, Shuaishuai
AU - Pei, Wenxiu
AU - Pang, Shufeng
AU - Zhang, Yunhong
N1 - Publisher Copyright:
© 2022
PY - 2022/4/1
Y1 - 2022/4/1
N2 - Understanding the efflorescence process of atmospheric aerosols is a key step towards a complete description of their phase transition dynamics. Atmospheric aerosols comprise internally mixed organic and inorganic components, and the composition of the condensed phase strongly affects the overall efflorescence dynamics. Although the kinetics of efflorescence has been thoroughly investigated for aerosols containing inorganic salts, the influence of non-ideal mixing with water-soluble organic compounds (WSOCs) remains considerably controversial. In this work, we measure the efflorescence process of ammonium sulfate (AS) aerosol droplets mixed with four types of WSOCs – sucrose, glycerol, malonic acid, and citric acid – by using attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. The absorbance band of ammonium ions (δ-NH4+ at 1441 cm−1) in the aqueous phase was used to calculate the crystallization ratio of AS and the heterogeneous nucleation rate. Adding WSOCs lowers the characteristic efflorescence relative humidity (ERH), broadens the ERH ranges, and reduces the terminal crystallization ratio of AS aerosol droplets. Amongst the various WSOCs studied here, the inhibiting effect on AS efflorescence decreases in the following order: sucrose > citric acid ≈ malonic acid > glycerol, mainly attributed to the mass transfer limitation caused by the viscosity of WSOCs. Sucrose and glycerol can completely suppress the crystallization of AS droplets at organic to inorganic ratio (OIR) of 1:1 and 4:1, respectively. This distinct observation suggests that atmospheric aerosols may skip efflorescence and evolve into a glassy state at low RH conditions.
AB - Understanding the efflorescence process of atmospheric aerosols is a key step towards a complete description of their phase transition dynamics. Atmospheric aerosols comprise internally mixed organic and inorganic components, and the composition of the condensed phase strongly affects the overall efflorescence dynamics. Although the kinetics of efflorescence has been thoroughly investigated for aerosols containing inorganic salts, the influence of non-ideal mixing with water-soluble organic compounds (WSOCs) remains considerably controversial. In this work, we measure the efflorescence process of ammonium sulfate (AS) aerosol droplets mixed with four types of WSOCs – sucrose, glycerol, malonic acid, and citric acid – by using attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. The absorbance band of ammonium ions (δ-NH4+ at 1441 cm−1) in the aqueous phase was used to calculate the crystallization ratio of AS and the heterogeneous nucleation rate. Adding WSOCs lowers the characteristic efflorescence relative humidity (ERH), broadens the ERH ranges, and reduces the terminal crystallization ratio of AS aerosol droplets. Amongst the various WSOCs studied here, the inhibiting effect on AS efflorescence decreases in the following order: sucrose > citric acid ≈ malonic acid > glycerol, mainly attributed to the mass transfer limitation caused by the viscosity of WSOCs. Sucrose and glycerol can completely suppress the crystallization of AS droplets at organic to inorganic ratio (OIR) of 1:1 and 4:1, respectively. This distinct observation suggests that atmospheric aerosols may skip efflorescence and evolve into a glassy state at low RH conditions.
KW - Efflorescence kinetics
KW - Inhibiting effect
KW - Mass transfer limitation
KW - Mixed aerosols
UR - http://www.scopus.com/inward/record.url?scp=85125114433&partnerID=8YFLogxK
U2 - 10.1016/j.atmosenv.2022.119007
DO - 10.1016/j.atmosenv.2022.119007
M3 - Article
AN - SCOPUS:85125114433
SN - 1352-2310
VL - 274
JO - Atmospheric Environment
JF - Atmospheric Environment
M1 - 119007
ER -